An example of image processing apparatus is a wall-mounting facsimile machine, which, in use, is mounted on a wall surface of a house. In use of such a wall-mounting facsimile machine, it is desired that the facsimile machine does not project greatly from the wall surface. Accordingly, there is a higher need for overall thickness reduction with respect to a wall-mounting facsimile machine than other type of facsimile machine used on a table or desk.
A prior art facsimile machine has the structure as shown in FIG. 11, for example, in which an image reading/writing head is accommodated in a machine housing. The illustrated image reading/writing head Y includes a head case 1 and a transparent cover 2 mounted on one side of the head case. The head case 1 accommodates light sources 3 for illuminating an image reading line L defined on the transparent cover 2, and lenses 5 for forming an image of a document. A substrate 4 is mounted on the other side of the head case 1. The substrate 4 has an obverse surface 4A and a reverse surface 4B which are provided with a plurality of light receiving elements 4a and a plurality of heat generating elements 4b, respectively. The light receiving elements and the heat generating elements are arranged in respective rows extending longitudinally of the substrate 4.
In the facsimile machine provided with the image reading/writing head Y having the above-described structure, a document D is transferred by a platen roller P1 in close contact with the transparent cover 2. During the transferring step, the document D is illuminated by the light sources 3. The light reflected by the document D is collected by the lenses 5, thereby forming an image of the document D on the light receiving elements 4a, which output image signals. On the other hand, a recording paper K of heat-sensitive type is transferred by a platen roller P2 in close contact with the heat generating elements 4b. During the transferring step, selected ones of the heat generating elements 4b generate heat, thereby printing an image on the recording paper K. The facsimile machine having the above-described structure can be made smaller in thickness than a facsimile machine in which a reading head and a printing head are separately provided.
However, in the above-described facsimile machine, the platen rollers P1, P2 are disposed so as to sandwich the image reading/writing head Y, so that the platen rollers P1 and P2 are bulky in the thickness direction of the image reading/writing head Y. Therefore, in the prior art described above, it is not possible to sufficiently reduce the thickness of the wall-mounting image processing apparatus. As a result, when apparatus is mounted, in use, on a wall surface, the apparatus projects greatly from the wall surface.